Hyaluronidase and hyaluronan in insect venom allergy.

BACKGROUND: Insect venoms contain an allergen hyaluronidase that catalyzes the hydrolysis of hyaluronan (HA), a polymer of disaccharide GlcUA-GlcNAc in skin. HAs depending on their size have variable function in inflammation and immunity. This paper reports on whether hyaluronidase, HA polymers and oligomers can promote antibody response in mice. METHODS: HA oligomers (8- to 50-mer; 3-20 kDa) were obtained by bee venom hyaluronidase digestion of HA polymers (750- to 5,000-mer; 300-2,000 kDa). Antibody responses in mice were compared following 3 biweekly subcutaneous injection of ovalbumin (OVA) with or without test adjuvant. RESULTS: OVA-specific IgG1 levels were approximately 2 times higher in BALB/c and C3H/HeJ mice receiving OVA and HA oligomer or polymer than those treated with OVA alone, and no increase in total IgE level was observed. In C57Bl/6 mice, observed increases in IgG1 and IgE were 3.5- and 1.7-fold, respectively, for the oligomer and 16- and 5-fold (p < 0.05), respectively, for the polymer. CONCLUSION: Hyaluronidase by its action on HA in skin can function indirectly as adjuvant to promote IgE and IgG1 response in mice. Insect venoms also have cytolytic peptides and phospholipases with inflammatory roles. These activities found in mice may contribute to venom allergenicity in susceptible people.

Structural and immunological characterization of the N-glycans from the major yellow jacket allergen Ves v 2: the N-glycan structures are needed for the human antibody recognition.

Yellow jacket (Vespula vulgaris) hyaluronidase (Ves v 2) is a glycoprotein and a mixture of two isoallergens, Ves v 2.01 and Ves v 2.02. Wasp and bee sensitized individuals frequently show IgE antibodies that in vitro recognize common carbohydrate structures across the hymenoptera species. The aim of the study was to characterize the glycosylation patterns in Ves v 2 isoallergens and to assess their immunological properties regarding antibody binding and T cell activation. The glycosylation sites and the carbohydrate structures were verified by use of tandem mass spectrometry (MS/MS). The immunological characterization of the N-glycan structures was assessed by antibody binding, T cell proliferation and T cell epitope assays comparing native (n) and non-glycosylated recombinant (r) Ves v 2. Analyses of the Ves v 2 glycopeptides revealed that glycan attachments were found for residues 79, 99 and 127 of Ves v 2.01, and residues 66 and 81 of Ves v 2.02. Structural analysis of the glycopeptides showed that the majority of the N-glycans contained at least one alpha1,3-fucose and/or alpha1,6-fucose residues in a structure. Interestingly, serum IgE antibodies from vespid allergic patients recognized nVes v 2 but not rVes v 2. Non-glycosylated rVes v 2, however, induced T cell and cytokine responses comparable to glycosylated nVes v 2. The present study shows that N-glycan structures are needed for the antibody recognition but not for the T cell reactivity of Ves v 2 in vitro. The occurrences of carbohydrate-specific antibodies against nVes v 2, however, suggest that non-mammalian glycan structures as in nVes v 2 may provide a link between T cells and other effector cells in allergic responses.

Strongyloides stercoralis recombinant NIE antigen shares epitope with recombinant Ves v 5 and Pol a 5 allergens of insects.

A new recombinant protein (NIE) for immunodiagnosis of human Strongyloides infection has 13% to 18% amino acid identity with antigen 5 insect venom allergen, but the C-terminal segment of NIE showed highest identity with Ves v 5 (yellow jacket) and Pol a 5 (paper wasp). A rabbit polyclonal anti-NIE antibody identified a single band of NIE antigen as well as bands of Pol a 5 and Ves v 5 antigens, and mouse anti-Pol a 5 and anti-Ves v 5 sera reacted with recombinant NIE antigen by Western blot. A cyanogen bromide-digested C-terminal fragment of NIE was reactive with mouse anti-Ves v 5 and Pol a 5 antibodies as well as with rabbit anti-NIE serum. Although IgE and IgG antibodies from pooled sera from Strongyloides-infected patients reacted with Pol a 5 and Ves v 5 recombinant antigens on immunoblots, neither antigen inhibited human IgG reaction with NIE antigen in a competitive enzyme-linked immunosorbent assay.

Inflammatory role of two venom components of yellow jackets (Vespula vulgaris): a mast cell degranulating peptide mastoparan and phospholipase A1.

BACKGROUND: Venom sac extract of yellow jackets Vespula vulgaris was toxic in mice when injected intraperitoneally but not toxic when injected subcutaneously. Necropsy showed the toxicity to be an inflammatory response. METHODS: Venom peptide and protein fractions were tested to identify the inflammatory components. The active components were tested to establish whether they might function as adjuvant for venom protein-specific antibody response. RESULTS: Venom toxicity required the synergistic action of two venom components, a mast cell degranulating peptide mastoparan and phospholipase A1. Both components stimulated prostaglandin E(2) release from murine peritoneal cells and macrophages. Mastoparan showed a weak activity to enhance IgE and IgG1 responses to a yellow jacket venom protein Ves v 5 in BALB/c mice. It was not possible to assess the adjuvant activity of phospholipase A1 because of its suppression of Ves v 5-specific response. Melittin, a mast cell degranulating peptide from bee venom, was inactive as an adjuvant for Ves v 5-specific response. CONCLUSION: Yellow jacket venom contains two inflammatory components, mastoparan and phospholipase A1. Our findings suggest that mastoparan can function as a weak adjuvant for TH2 cell-associated antibody response.

Microarrayed allergen molecules: diagnostic gatekeepers for allergy treatment.

Type I allergy is an immunoglobulin E (IgE)-mediated hypersensitivity disease affecting more than 25% of the population. Currently, diagnosis of allergy is performed by provocation testing and IgE serology using allergen extracts. This process defines allergen-containing sources but cannot identify the disease-eliciting allergenic molecules. We have applied microarray technology to develop a miniaturized allergy test containing 94 purified allergen molecules that represent the most common allergen sources. The allergen microarray allows the determination and monitoring of allergic patients' IgE reactivity profiles to large numbers of disease-causing allergens by using single measurements and minute amounts of serum. This method may change established practice in allergy diagnosis, prevention, and therapy. In addition, microarrayed antigens may be applied to the diagnosis of autoimmune and infectious diseases.